Headspace modification method for removal of vacuum pressure and apparatus therefor

ABSTRACT

To modify the headspace in a container to remove vacuum pressure, a container has a seal or cap which may provide a temporary opening into the container which is sealable under compression to provide a controlled raising of the internal pressure as the heated contents of the container cools. A sealing chamber ( 84 ) may enable the introduction of a fluid into the headspace ( 23   b ) to force the fluid level ( 40 ) lower. Other methods and apparatus are described.

TECHNICAL FIELD OF THE INVENTION

This invention relates generally to a method of light-weighting hot fillcontainers by modifying the headspace for the removal of vacuum pressureand apparatus therefor. This is achieved by filling a container with aheated fluid; which term for the purposes of this specificationincluding both liquids and gases unless specified otherwise, sealing thecontents of the container from contamination from outside air, andadjusting the pressure of the headspace during the capping process tonegate vacuum forces generated within the container following fluidcooling. The headspace modification process displaces the fluid belowthe headspace in the upper neck region of the container downwardly priorto allowing the fluid contents to cool, and labelling the container.This invention further relates to hot-filled, and pasteurized productspackaged in heat-set polyester containers and is particularly useful forpackaging oxygen sensitive foods and beverages where a longer shelf lifeis desirable.

BACKGROUND

So called ‘hot fill’ containers are well known in prior art, wherebymanufacturers supply PET containers for various liquids which are filledinto the containers and the liquid product is at an elevatedtemperature, typically at or around 85 degrees C. (185 degrees F.).

The container is manufactured to withstand the thermal shock of holdinga heated liquid, resulting in a ‘heat-set’ plastic container. Thisthermal shock is a result of either introducing the liquid hot atfilling, or heating the liquid after it is introduced into thecontainer.

Once the liquid cools down in a capped container, however, the volume ofthe liquid in the container reduces, creating a vacuum within thecontainer. This liquid shrinkage results in vacuum pressures that pullinwardly on the side and end walls of the container. This in turn leadsto deformation in the walls of plastic bottles if they are notconstructed rigidly enough to resist such force.

Typically, vacuum pressures have been accommodated by the use of vacuumpanels, which distort inwardly under vacuum pressure. Prior art revealsmany vertically oriented vacuum panels that allow containers towithstand the rigors of a hot fill procedure. Such vertically orientedvacuum panels generally lie parallel to the longitudinal axis of acontainer and flex inwardly under vacuum pressure toward thislongitudinal axis.

In addition to the vertically oriented vacuum panels, many prior artcontainers also have flexible base regions to provide additional vacuumcompensation. Many prior art containers designed for hot-filling havevarious modifications to their end-walls, or base regions to allow foras much inward flexure as possible to accommodate at least some of thevacuum pressure generated within the container.

Even with such substantial displacement of vacuum panels, however, thecontainer requires further strengthening to prevent distortion under thevacuum force.

The liquid shrinkage derived from liquid cooling, causes a build up ofvacuum pressure. Vacuum panels deflect toward this negative pressure, toa degree lessening the vacuum force, by effectively creating a smallercontainer to better accommodate the smaller volume of contents. However,this smaller shape is held in place by the generating vacuum force. Themore difficult the structure is to deflect inwardly, the more vacuumforce will be generated. In prior art proposals, a substantial amount ofvacuum may still be present in the container and this tends to distortthe overall shape unless a large, annular strengthening ring is providedin horizontal, or transverse, orientation typically at least a ⅓ of thedistance from an end to the container.

The present invention relates to hot-fill containers and may be used byway of example in conjunction with the hot fill containers described ininternational applications published under numbers WO 02/18213 and WO2004/028910 (PCT specifications) which specifications are alsoincorporated herein in their entirety where appropriate.

The PCT specifications background the design of hot-fill containers andthe problems with such designs that were to be overcome or at leastameliorated.

A problem exists when locating such transversely oriented panels in thecontainer side-wall, or end-wall or base region, even after vacuum isremoved completely from the container when the liquid cools down and thepanel is inverted. The container exits the filling line just above atypical ambient temperature, and the panel is inverted to achieve anambient pressure within the container, as opposed to negative pressureas found in prior art. The container is labelled and often refrigeratedat point of sale.

This refrigeration provides further product contraction and incontainers with very little sidewall structure, so-called ‘glasslook-a-like’ bottles, there may therefore be some panelling that occurson the containers that is unsightly. To overcome this, an attempt ismade to provide the base transverse panel with more extraction potentialthan is required, so that it may be forced into inversion against theforce of the small headspace present during filling. This creates asmall positive pressure at fill time, and this positive pressureprovides some relief to the situation. As further cool down occurs, forexample during refrigeration, the positive pressure may drop and mayprovide for an ambient pressure at refrigerated temperatures, and soavoid panelling in the container.

This situation is very hard to engineer successfully, however, as itdepends on utilising a larger headspace in order to compress at baseinversion time, and it is less desirable to introduce a larger headspaceto the container than is necessary in order to retain product quality.

While it is desirable to have the liquid level in the container drop, toavoid spill when opened by the consumer, it has been found thatproviding too much positive pressure potential within the base may causesome product spill when the container is opened, particularly if atambient temperatures.

In most filling operations, containers are generally filled to a leveljust below the container's highest level, at the top of the neck finish.

Maintaining as small a container headspace as possible is desirable inorder to provide a tolerance for subtle differences in product densityor container capacity, to minimize waste from spillage and overflow ofliquids on a high-speed package filling line, and to reduce containercontraction from cooling contents after hot fill.

Headspace contains gases that in time can damage some products or placeextra demands on container structural integrity. Examples includeproducts sensitive to oxygen and products filled and sealed at elevatedtemperatures.

Filling and sealing a rigid container at elevated temperatures cancreate significant vacuum forces when excessive headspace gas is alsopresent.

Accordingly, less headspace gas is desirable with containers filled atelevated temperatures, to reduce vacuum forces acting on the containerthat could compromise structural integrity, induce container stresses,or significantly distort container shape. This is also true duringpasteurization and retort processes, which involve filling the containerfirst, sealing, and then subjecting the package to elevated temperaturesfor a sustained period.

Those skilled in the art are aware of several container manufacturingheat-set processes for improving package heat-resistant performance. Inthe case of the polyester, polyethylene terephthalate, for example, theheat-setting process generally involves relieving stresses created inthe container during its manufacture and to improve crystallinestructure.

Typically, a polyethylene terephthalate container intended for acold-fill carbonated beverage has higher internal stresses and lesscrystalline molecular structure than a container intended for ahot-fill, pasteurized, or retort product application. However, even withcontainers such as described in the abovementioned PCT specificationswhere there is little residual vacuum pressure, the neck finish of thecontainer is still required to be very thick in order to withstand thetemperature of fill.

My PCT patent specification WO 2005/085082 describes a previous proposalfor a headspace displacement method which is incorporated herein in itsentirety where appropriate by way of reference.

Where reference in this specification is made to any prior art this isnot an acknowledgment that it forms part of the common general knowledgein any country or region.

OBJECTS OF THE INVENTION

In view of the above, it is an object of one possible embodiment of thepresent invention to provide a headspace sealing and modification methodthat can provide for removal of vacuum pressure such that there issubstantially no remaining force within the container.

It is a further object of one possible embodiment of the presentinvention to provide a headspace compression method whereby air, or someother gas or liquid or combination thereof, is charged into theheadspace under sealed pressure to create an increased pressure in orderto negate the effect of vacuum pressure created during cooling of theproduct.

It is a further object of one possible embodiment of the presentinvention to provide a headspace modification method whereby sterile orheated liquid, or air, or some other gas or combination thereof, ischarged into the headspace under sterile conditions to create a positivepressure in order to negate the effect of vacuum pressure created duringcooling of the product.

It is a further object of one possible embodiment of the presentinvention to provide a headspace modification method whereby sterileair, or some other gas or liquid or combination thereof, is charged intothe headspace under sealed pressure to negate the effect of vacuumpressure created during cooling of the product.

It is a further object of one possible embodiment of the presentinvention to provide a headspace modification method whereby acompressive seal is applied to the neck finish of the container.

It is a further object of one possible embodiment of the presentinvention to provide a headspace displacement method whereby acompressive seal is applied to the neck finish that is forciblydisplaceable into the container prior to cooling the liquid contents,such that a positive pressure may be induced into the container.

A further and alternative object of the present invention in all itsembodiments, all the objects to be read disjunctively, is to at leastprovide the public with a useful choice.

SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided acontainer having a seal or cap including, or adapted to provide, anopening or aperture into said container, said aperture providing for theintroduction under pressure of at least one fluid, said opening oraperture also being sealable to provide a controlled raising of internalpressure within the container prior to cooling of heated contents withinthe container.

According to a further aspect of the present invention there is provideda container having a seal or cap temporarily applied such that anopening or aperture into said container is provided by an incompleteseal being formed between the cap and a neck finish of the container,said opening or aperture providing for the introduction under pressureof at least one fluid, said opening or aperture also being sealableunder compression to provide a controlled raising of internal pressurewithin the container prior to cooling of heated contents within thecontainer.

According to a further aspect of the present invention there is provideda container having a seal or cap providing a temporary seal immediatelypost-filling and having an aperture or opening, said aperture or openingbeing accessible under substantially sterile conditions to provide forthe introduction of at least one heated and/or sterile fluid, saidaperture or opening also further being sealable under substantiallysterile conditions to provide a controlled raising of internal pressurewithin the container following cooling of heated contents within thecontainer.

According to a further aspect of the invention a method of filling acontainer with a fluid includes introducing the fluid through an openend of the container so that it, at least substantially, fills thecontainer, heating the fluid before or after its introduction into thecontainer, providing a seal or cap having an opening or aperture,providing a method of providing at least one fluid through the openingor aperture and sealing the opening or aperture, so as to compensate forsubsequent pressure reduction in a headspace of the container under theseal or cap following the cooling of the heated contents.

According to a further aspect of the invention a method of filling acontainer with a fluid includes introducing the fluid through an openend of the container so that it, at least substantially, fills thecontainer, heating the fluid before or after its introduction into thecontainer, providing a seal or cap having an opening or aperture, saidopening or aperture being initially sealed, providing for the heatedcontents to cool, further providing a method of subsequently accessingthe opening or aperture and injecting at least one fluid through theopening or aperture and sealing the aperture, so as to compensate forthe pressure reduction in the headspace of the container following thecooling of the heated contents.

According to a further aspect of the present invention there is provideda container having an upper portion with an opening into said container,said upper portion having a neck finish adapted to include, subsequentto the introduction of a heated or heatable liquid into the container, aseal, said seal being inwardly compressible or mechanically moveablebefore or after the liquid is heated, so as to increase the pressure ofthe headspace.

According to a further aspect of the invention a method of filling acontainer with a fluid includes introducing the fluid through an openend of the container so that it, at least substantially, fills thecontainer, heating the fluid before or after its introduction into thecontainer, providing a moveable seal for the open end to cover andcontain the fluid, said seal being adapted to compress a headspace ofthe container so as to compensate for subsequent pressure reduction inthe headspace of the container under the seal as the heated contentscool.

According to a further aspect of the invention there is provided acontainer filling apparatus for filling a container or performing afilling method as defined in the above seven paragraphs.

According to a further aspect there is provided a seal or cap for acontainer configured for use: with any one of embodiments of thecontainer of the invention or in any one of the embodiments of themethod of the invention or with any one of the embodiments of thecontainer filling apparatus of the invention.

According to a further aspect, there is provided a seal or cap for acontainer including the features of the seal or cap set out in any oneof the first three aspects above to the container of the invention.

Further aspects of the invention which should be considered in all itsnovel aspects will become apparent from the following description.

BRIEF DESCRIPTION OF DRAWINGS

FIGS. 1 a-b & 2 a-2 b: show embodiments of a prior art container from WO2005/085082 with a mechanically compressible cap applied to seal thebeverage;

FIGS. 3 a-b: show a further prior art use from WO 2005/085082 of acompressed cap of FIGS. 1 and 2;

FIGS. 4 a-b & FIG. 5 a-c: show a container and cap according to apossible embodiment of the invention;

FIGS. 6 a-c: show a further embodiment of the invention using a sealingchamber;

FIGS. 7 a-c, FIGS. 8 a-c, FIGS. 9 a-c, FIGS. 10 a-f, FIG. 11 a-c, FIGS.12 a-c, FIGS. 13 a-c, FIGS. 14 a-c & FIGS. 15 a-c: show furtherembodiments of the invention using a sealing chamber;

FIGS. 16 a-c: show a further possible embodiment of this invention;

FIGS. 17 a-c: show a further possible embodiment of this invention;

FIG. 18: shows a further possible embodiment of the invention using asealing chamber;

FIGS. 19 a-b: show a possible embodiment of the invention in the form ofa capping machine;

FIGS. 20 a-b & FIGS. 21 a-b: show a show a further possible embodimentof the invention using a pressure chamber;

FIGS. 22 a-c & FIGS. 23 a-c: show diagrammatically a possible method ofthe present invention;

FIGS. 24 to 27: show diagrammatically a further possible embodiment ofthe invention in the form of a capping machine; and

FIGS. 28 a-d, 29 a-d & FIGS. 30 a-b: show further embodiments of theinvention using a sealing chamber.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The following description of preferred embodiments is merely exemplaryin nature, and is in no way intended to limit the invention or itsapplication or uses.

As discussed above, to accommodate vacuum forces during cooling of thecontents within a heat set container, containers have typically beenprovided with a series of vacuum panels around their sidewalls and anoptimized base portion. The vacuum panels deform inwardly, and the basedeforms upwardly, under the influence of the vacuum forces. Thisprevents unwanted distortion elsewhere in the container. However, thecontainer is still subjected to internal vacuum force. The panels andbase merely provide a suitably resistant structure against that force.The more resistant the structure the more vacuum force will be present.Additionally, end users can feel the vacuum panels when holding thecontainers.

Typically at a bottling plant the containers will be filled with a hotliquid and then capped before being subjected to a cold-water sprayresulting in the formation of a vacuum within the container that thecontainer structure needs to be able to cope with. The present inventionrelates to hot-fill containers and a method that provides for thesubstantial removal or substantial negation of vacuum pressure. Thisallows much greater design freedom and light weighting opportunity asthere is no longer any requirement for the structure to be resistant tovacuum forces that would otherwise mechanically distort the container.

As seen in a Prior Art solution in FIGS. 1 a to b and 2 a to 2 b, whenhot liquid (21) is introduced to a container (1), the liquid occupies avolume that is defined by a first upper level (3 a). Should acompressive cap (8) be applied immediately post fill to a container neck(2), then a vacuum builds up in the headspace (23 b) that is above theliquid and under the sealing surface (10) of the compressive cap, thesealing surface being the lower border of the compressible inner chamber(9) which is engaged with the outer portion of the cap (8). Thisheadspace vacuum is normally only released when the cap is removed.While the cap (8) remains in place then the vacuum force remains largelyunchanged. If the walls of the container bend or flex inwardly then thevacuum pressure level may drop to a small degree.

Referring to FIGS. 3 a-b shows a further embodiment of Prior Artinvention.

However, as disclosed in the Prior Art, as illustrated in FIGS. 2 a-b,mechanical compression of the moveable seal within the cap structure toachieve a positive pressure occurs only once the container has cooled.This has the distinct disadvantage of moving unsterilized wall surfacesof the cap components into communication with the liquid contents of thecontainer. This contamination can not be tolerated and so an embodimentof the present invention provides only for this mechanical compressionof the headspace to occur immediately post application of the cap.

In this way mechanical compression can achieve a positive pressure whilethe contents of the container are in a heated state, and to subsequentlyenable the container to be cooled without panelling. The cap componentsthat enter the container headspace under compression will be sterilisedtherefore by the heated contents prior to cooling. It will beappreciated that many different structures are envisaged for providing aprimary sealing structure that is forcible downwards to displace theliquid contents to a large degree. Containers of the 600 ml size forexample will require displacement to the order of 20-30 cc of liquid.Containers of the 2000 ml range of size will require displacement to theorder of 70 cc of liquid.

It is envisaged that the cap may be of metal or plastics and could inalternative embodiments be pushed into the neck of the container ratherthan screwed and could be lockable in a required position.

The cap may be controllably displaced downwardly by any suitablemechanical or electrical or other means, or manually.

The method of the present invention allows many variables in mechanicalcompression to be accounted for, but for larger containers wheresignificant downward displacement would be required it is envisaged thatonly some of the compressive force would be obtained from a compressivecap and, more significantly, the remainder would be obtained by themethods discussed in the following disclosure.

Referring to FIGS. 4 a and b, an exemplary embodiment of the presentinvention is shown with a cap (80) engaged with the container neck (2).Figures onward from 4 a all refer to upper portions of containers assimilarly shown in FIG. 4 a.

According to a further aspect of the present invention, and referring toFIGS. 4 a and b, and FIGS. 5 a-c, following the introduction of aliquid, which may be already heated or suitable for subsequent heating,a cap may be applied including a small opening or aperture (81). Thus aheadspace (23 a) is contained under the main cap body (80) and above thefluid level (40) in the container. The headspace (23 a) is communicatingwith the outside air at this stage and is therefore at ambient pressureand allowing for the fluid level (40).

As seen in FIGS. 6 a-c, in one embodiment a sealing chamber (84) isapplied over the neck finish and cap combination to seal the liquid fromthe outside air (the upper, closed end of the structure 84 is notshown). Following the introduction of a compressive force, as indicatedby the arrows, for example by way of injecting air or some other gas,the increased pressure within the sealing chamber provides for asubsequent increase in pressure within the headspace (23 b) and alsoforces the fluid level (40) to a lower point due to the subsequentexpansion of the plastic container.

As an alternative to the injection of gas, a heated liquid could beinjected, for example heated water. This would provide furtheradvantage, in that the liquid injected would not be subject to theexpansion that would normally occur when injecting gas into a heatedenvironment. Thus less force would be ultimately applied to thesidewalls of the container during the early hot-fill stages.

Even further, the injected liquid would contract less than a gas whensubsequently cooled. For this reason less liquid is necessarily requiredto be injected into the headspace to provide compensation for theanticipated vacuum forces that would otherwise occur.

Now referring to FIGS. 7 a-c (the compressive force not shown), whilepressure is maintained within the sealing chamber (84), a plug mechanism(82) is moved downwardly from a delivery device (83) towards theaperture (81). As can be seen in FIGS. 8 a-c, while pressure ismaintained within the sealing chamber (84), the hole is closed offpermanently by the placement of the plug (82) into the hole (81).

At this point, and as can be seen in FIGS. 9 a-c, the headspace (23 b)is charged under a controlled pressure, dependant on the amount of gasdelivered, and the sealing chamber may provide for withdrawal of thedelivery device (83) following a release of pressure within the chamberas the container is ejected and returned to the filling line.

As shown in FIGS. 10 a-c, as the bottle subsequently travels down thefilling line and is cooled, the headspace (23 b) expands as the liquidvolume shrinks. The fluid level (40) lowers to a new position (41) andthe pressurised headspace (23 b) expands and loses some or all of itspressure as it forms a new headspace (23 c).

Importantly, however, once the contents are cooled there is no residualvacuum in the container.

As an alternative, and as shown in FIGS. 10 d-f, the plug 92 may betemporarily attached to the cap, for example by member 91, duringproduction of the cap. A liquid, as in the example illustrated, or gas,could be injected in the same manner under pressure to circumnavigatethe plug and enter the container headspace under pressure, and a rodmechanism 93 is then forced downwardly to advance the plug 92 into thehole permanently. In this alternative there is no need to load the rodwith multiple plug mechanisms.

A further example of such an alternative is provided in FIG. 18. In thisembodiment of the invention the cap 80 has a plug 92 temporarilyattached by a member (not shown). A sealing chamber 84 encloses the capand provides an internal sealed chamber headspace 87 through thecompression of sealing rings 89 against the upper surface of the cap.Gas or liquid, or a combination of both, is injected into the chamberheadspace 87 through an inlet 86 and through the spaces around the pluginto the headspace of the container. Once the required pressure withinthe container is obtained, the push rod 88 is advanced downwardly toforce the plug 92 into position within the cap and therefore seal thecontainer headspace under the required pressure. This provides for acalculated internal pressure to be achieved precisely at the time ofsealing the container, when the plug is advanced into final position.This provides for forward compensation of the effects of subsequentvacuum generated by a cooling of any heated contents within thecontainer.

With reference to FIGS. 19 a and 19 b, the present invention may bemanufactured to function along very similar lines to a typical cappingstation on a filling line. A typical capping machine head unit 101encapsulates the sealing unit 84 and provides the function of sealingand pressurising the container through the cap to seal the container. Atypical capping unit may have optionally already torqued the cap intoposition, but the container would remain unsealed due to the presence ofa plug being in an ‘unplugged’ position within the cap and allowing thepassage of liquid or gas between the inside and outside of thecontainer. The precise moment of sealing the container occurs as theplug is rammed into position and the headspace within the cap is not atambient pressure, as would be typical of prior art capping procedureswithin the filling and capping area, but instead with the presentinvention a headspace modification unit 102 may receive cappedcontainers 1, and subsequently pressurise the container immediatelyprior to sealing the container with a cap sealing plug.

As an alternative, the headspace modification unit 102 could alsoperform the usual function of a typical capping machine. The unit couldreceive empty containers, apply caps containing the plugs andsubsequently torque the caps into position as well as pressurise thecontainer prior to ultimately sealing the container through advancingthe plug or some other sealing method.

Still further examples of alternative embodiments of the presentinvention are illustrated in FIGS. 20 a-f. The cap 80 may incorporate arubber, or other suitable material, plug 182 within the cap. This wouldprovide the advantage of having an initially leakproof seal to thecontainer prior to pressurising the headspace. In this way, thecontainer could be charged with pressure from a liquid or gas eitherprior to the cooling of the contents, for example immediately afterfilling and capping by way of overpressure, or the procedure could occurafter the contents have been cooled and there is a vacuum within thecontainer. By way of example, the cap and sealing plug 182 could besterilized by very hot water 66 after the liquid contents have cooled.This would sterilize the upper surface of the cap and a heated liquidcould then be injected to compensate for vacuum pressure. Followingwithdrawal of the injecting needle 202, the sterilizing heated liquidcould be removed as the container is ejected from the pressure chamber.The rubber seal 182 would have closed off and sealed the container toprevent any communication between the headspace under the cap andoutside air present as the chamber is opened.

A further alternative for a suitable plug mechanism within a cap 80 isillustrated in FIGS. 21 a-f. A ball-valve type closure 882 could beutilized to provide a hole through which headspace modification mayoccur within the pressure chamber unit as previously described. Once theheadspace has been pressurized, a rotating push rod 883 can close theball valve while the headspace is maintained under exact pressure asillustrated in FIGS. 21 d-f.

FIGS. 22 a-c shows a typical example method of headspace modificationusing the method of the present invention. An empty container (not shownbelow the neck finish) is filled or even ‘overfilled’ to the brim of theneck finish, and a cap is applied that has an opening through whichheadspace modification can be achieved, for example a ball-valve closuredevice. The capped neck finish, at least, is contained within a pressurechamber (not shown) and the container is placed under a calculatedpressure. This increase in pressure may be by injection of a gas as inthe illustrated example, or by over injection of further liquid. Duringthis process the container will increase in size to a degree allowingthe fluid level to drop (if gas is being injected) and the ball-valveclosure may then be closed to maintain the increased pressure within thecontainer.

The same method procedure may occur using a more typical ‘push-pull’type sport closure as illustrated in similar manner in FIGS. 23 a-c.

As a further alternative to the present invention, and to remove theneed for a hole or plug mechanism within the cap itself, and withreference to FIGS. 17 a-c, a normal cap could be applied by a cappingunit but not forcibly torqued into position. The neck finish can then beenclosed within the chamber 84 and the liquid or gas forced into thecontainer through the gap between the cap and the thread mechanisms ofthe neck finish, as shown by passage of liquid 86. Once the desiredpressure is obtained the cap, as shown in FIG. 17 b, can then be torquedinto position by advancing the torque rod 85 within the chamber 84 whileholding the container headspace at pressure. In this embodiment themethod may be achieved using standard caps rather than modified caps.FIG. 17 c illustrates removal of the torque rod 85, correctly torquedcap 80, immediately prior to ejecting the container head from thechamber 84.

It will be appreciated that the present invention offers multiplechoices in carrying out a headspace modification procedure by way ofmodifying a typical capping machine. Such a piece of machinery couldeasily be employed to also provide the function of capping the containerin addition to modifying the headspace during the procedure.

FIG. 24 shows how a container could be contained within a typicalsealing chamber 84 from immediately below the neck support ring 33 ofthe container.

FIG. 25 illustrates how the whole container could be contained within asealing chamber 84. In this embodiment the container will not bestressed from the increased pressure until after ejection from thesealing chamber.

FIG. 26 shows an alternative embodiment of the present invention. It isenvisaged that the sealing chamber 84 could comprise optionally a lowerend sealing skirt 884. In this example, a sealing ring of soft materialmay be inflated under pressure of water or gas through an inlet 883 toform a close contact with the container shoulder. Gas or liquid may thenbe charged into the pressure chamber headspace 87 through inlet 86 tomodify the container headspace prior to final sealing.

FIG. 27 shows how the sealing chamber of FIG. 26 could be incorporatedinto a typical capping unit station with rotary head applicators. Thiswould allow for a modified capping unit to apply a cap in the normalmanner, but to modify the headspace prior to application of torque toseal the cap on the container.

In facilitating the present invention, the complete or substantialremoval of vacuum pressure by displacing the headspace prior to theliquid contraction now results in being able to remove a substantialamount of weight from the sidewalls due to the removal of mechanicallydistorting forces.

According to a further aspect of the present invention, and referring toFIGS. 11 a-c, following the introduction of a liquid, which may bealready heated or suitable for subsequent heating, a cap may be appliedincluding a small opening or aperture (81) which is temporarily coveredby a communicating seal (91). Thus a headspace (23 d) is contained underthe main cap body (80) and above the fluid level (40) in the container.The headspace (23 d) is not communicating with the outside air at thisstage and is therefore at typical container pressure during the stagesof cooling down on the filling line.

As seen in FIGS. 12 a-c, once the container has been typically cooled toa level providing for labelling and distribution the headspace (23 e)will be in an expanded state with a lowered fluid level, and will havecreated a vacuum due to the contraction of the heated liquid within thecontainer.

As seen in this preferred embodiment of the present invention, in orderto remove the vacuum pressure a sealing chamber (84) is applied over theneck finish and cap combination to seal the communicating seal (91) fromthe outside air (the upper, closed end of the structure 84 is notshown).

Following the introduction of a sterilising medium (66), for example byway of injecting heated water, preferably above 95 degrees C., or amixture of heated water and steam, the sterilising medium provides forthe sterilisation of the internal surfaces of the sealing chamber (84)and the communicating seal (91).

Now referring to FIGS. 13 a-c, while the sterilising medium ismaintained within the sealing chamber (84), a plug mechanism (82) isplaced downwardly from a delivery device (83) towards the aperture (81).The plug mechanism pierces the communicating seal (91) and is withdrawnagain temporarily as shown in FIGS. 14 a-c, providing for communicationbetween the sterilized volume within the sealing chamber above the cap(80) and the headspace (23 e) below the cap.

As can be seen in FIGS. 14 a-c, the sterilising medium, for exampleheated water at 95° C., is immediately drawn into the container throughthe open hole (81) due to the communicating seal being pierced. Thiscauses equalization of pressure or removal of vacuum pressure within thecontainer, such that the level of the headspace (23 f) rises higher. Inanother preferred embodiment the liquid would in fact be injected intothe container under a small pressure supplied from the sealing chamber(84) such that the pressure within the container would in fact be apositive pressure and the headspace would in fact be very small.

The integrity of the product volume within the container is notcompromised as the environment above the cap has been sterilised priorto communicating with the headspace, and the additional liquid suppliedinto the container replaces the volume ‘lost’ due to shrinkage of heatedliquid within the container prior to the method of headspace replacementdescribed.

Following the pressure equalization, and now referring to FIGS. 15 a-c,the delivery device (83) is advanced again such that the plug (82) willbe injected into the hole to close it off permanently.

At this point, the headspace (23 f) is under a controlled pressuredependent on the volume of liquid having been delivered to compensatefor previous liquid contraction, as described above.

The sealing chamber may now provide for withdrawal of the deliverydevice (83) which may now be done following a release of sterilisingmedium and/or pressure within the chamber as the container is ejectedand returned to the filling line.

Thus a method of compensating vacuum pressure within a container isdescribed. Referring to FIGS. 16 a-c, the original headspace level (40)experienced following cooling of heated contents within a closedcontainer provides for a vacuum to be present within the first headspace(23 d). Following compensation according to this embodiment of thepresent invention the headspace level changes and perhaps rises (41)depending on the pressure contained within the headspace and thepressure within the headspace 23 f is now preferably virtually atambient pressure or preferably slightly positive such that the sidewallsof the container are supported by the slight internal pressure.

With reference to FIGS. 28 a-d, an alternative embodiment of the presentinvention also incorporates a compressible cap wherein the compressionoccurs after filling and prior to the cooling of the contents. In thisway, by compression occurring when the liquid is hot, the chamber (9)may be sterilized by the contents once it is advanced into thecontainer. The compressible cap may be contained within a compressionchamber as previously described, particularly for large size containers.Containers of the 600 ml size for example will require displacement tothe order of 20-30 cc of liquid, but containers of the 2000 ml range ofsize will require displacement to the order of 70 cc of liquid. Such alarge displacement is difficult to achieve without having an extremelylarge displaceable chamber entering the container. Therefore, in orderto keep the chamber size to a minimum, it is envisaged that thecompression chamber could provide an injection of a certain amount ofgas or liquid, and a compressible cap could provide the rest of thecompression required. In this way a minimum of gas is also injected intothe container. Of course, for small container sizes it will beappreciated that just the compressible cap could be utilised.

Unlike as described in prior art, the present invention provides for thehot liquid within the container to sterilize the underside of theinternally presented surface of the inner chamber (9) as it has beencompressed into the hot liquid contents.

Ordinarily, as the product cools, a vacuum will build up within thecontainer in the primary headspace (23 b) under the cap. This vacuum maydistort the container (1) to a degree if the walls are not rigid enoughto withstand the force.

However, as the internal pressure has been adjusted upwardly prior toproduct cooling, the net effect may be a temporary raised level ofpressure during product cooling and substantially no pressure onceproduct cooling has finished, or perhaps even advantageously a smallamount of positive pressure.

Referring to FIGS. 29 a-d, another similar embodiment of the presentinvention provides for a mechanical cap that has a mechanicallycontrollable “out” and “in” position. The compressive cap (8) is appliedto the container (1) immediately post filling with a hot beverage. Inthis particular embodiment the sealing surface (10) of the compressibleinner chamber (9) is displaced higher than in the previous example shownin FIGS. 28 a-d.

Referring to FIGS. 30 a-b, a further embodiment of the present inventionis disclosed. The cap structure may be either a 2-piece construction, ora single unit whereby the compressible inner chamber (9) engages with aninternal thread on the neck finish (99) and causes compression of theheadspace as the cap is applied and secured to the container (1). Again,for larger size containers this provides the ability to keep gas orliquid injection to a minimum while utilising the displacement of thehot liquid contents to provide the increase in container pressure as thecontainer is sealed.

Where in the foregoing description, reference has been made to specificcomponents or integers of the invention having known equivalents thensuch equivalents are herein incorporated as if individually set forth.

Although this invention has been described by way of example and withreference to possible embodiments thereof, it is to be understood thatmodifications or improvements may be made thereto without departing fromthe scope of the invention as defined in the appended, claims.

1. A container having a seal or cap including, or adapted to provide, anopening or aperture into said container, said opening or apertureproviding, in use, for the introduction under pressure of at least onefluid, said opening or aperture also being sealable, under pressure, inuse, to provide an increased internal pressure within the container. 2.A container as claimed in claim 1 wherein said at least one fluid isintroduced under pressure and said opening or aperture is sealable undercompression.
 3. A container as claimed in claim 2 wherein said seal orcap is temporarily applied such that said opening or aperture isprovided by an incomplete seal being formed between the seal or cap anda neck finish of the container.
 4. A container as claimed in claim 1wherein said seal or cap provides a temporary sealing means afterfilling of the container, said opening or aperture being accessibleunder substantially sterile conditions to provide for the introductionof said at least one fluid.
 5. A container as claimed in claim 4 whereinsaid at least one fluid is heated and/or sterile and said opening oraperture is further adapted to be sealable under substantially sterileconditions to provide said controlled raising of internal pressure.
 6. Acontainer as claimed in claim 1 in which said at least one fluid is aheated liquid or a gas injected through said opening or aperture.
 7. Acontainer as claimed in claim 6 in which said opening or aperture isadapted to be permanently closed following the injection of said liquidor gas.
 8. A container as claimed in claim 1 in which said cap iscompressible within a neck of the container towards its interior.
 9. Acontainer as claimed in claim 1 in which said opening or apertureincludes a valve means which is operable to open and close said openingor aperture.
 10. (canceled)
 11. A method of filling a container with afluid including introducing the fluid through an open end of thecontainer so that it, at least substantially, fills the container,heating the fluid before or after its introduction into the container,providing a seal or cap having an opening or aperture, providing atleast one fluid through the opening or aperture and sealing the openingor aperture under pressure so as to compensate for subsequent pressurereduction in a headspace of the container under the seal or capfollowing the cooling of the heated contents.
 12. A method as claimed inclaim 11 in which the at least one fluid passes through the opening oraperture under pressure.
 13. A method as claimed in claim 12 in whichthe container is positioned in a pressurizing means.
 14. A method asclaimed in claim 11 in which the container is positioned in asterilizing means and the fluid is a heated liquid injected through theopening or aperture.
 15. A method as claimed in claim 11 in which theopening or aperture is provided with a temporary or partial seal throughwhich the at least one fluid is provided.
 16. A method as claimed inclaim 11 in which a neck of the container is provided with acompressible cap which is moveable within the neck towards the heatedcontents before the heated contents have cooled.
 17. (canceled)
 18. Acontainer filling apparatus for filling a container as claimed inclaim
 1. 19. A container when filled by the method of claim
 11. 20. Acap for a container, the cap being adapted for use with the container ofclaim
 1. 21. A container filling apparatus for performing the method ofclaim
 14. 22. A container when filled by the apparatus of claim
 18. 23.A cap for a container, the cap being adapted for use with the apparatusof claim 16.